Electrically-driven clock



April 22, 1930. F. HOLDEN ELECTRIGALLY DRIVEN CLOCK Filed 001:. 19

Hill

m m %M B m V0 1 1% J l m 1. $1 H INVENT B W W H15 ATTOANE).

Patented Apr. 22, 1930 UNITED STATES.

FICE

ELECTRICALLY-DRIVEN CLOCK Application filed October 19,, 1927, Serial No.

The object of the present invention is to provide a clock movement in which the motion of an oscillating member is maintained electro-magnetically.

The movement of the present invention is of the type in which a coil carried by the oscillating member passes periodically through the field of a permanent magnet and receives at the desired moment a current, causing it to be displaced with respect to themagnet in order to maintain the movement of the oscil lating member, the circuit of the coil being controlled by two contacts of which'one isdisplaced with the oscillating member while the other contact is displaced under the action of the first, but is normally in a position of rest to which it is returned. The present invention'is distinguished on the other hand by the fact that the return of the second contact takes place by gravity so that this return takes place in a constant manner during the progress of the movement.

The accompanying drawing illustrates by Way of an example one mode of constructing a clock movement according to the present invention, Figs 1 and 2 being respectively a 'front' view and a side elevation partly in section, and Fig. 3 is a detail plan view.

Referring to the drawing the spindle 4 carries a balance wheel 5, constructed by a cross piece 6 and two arcuate parts 7 and pivots between two jewels secured in horizontal arms 2, 3, with which the single support plate 1 is provided. The spindle is provided towards its upper end with an arm 13 at one of the ends of which is located a fiat-coil 14 passing in the course of its oscillations through an air gap 15 arranged between two pole pieces 16, 17 of circular cross-section. These pole pieces are carried by two plates 18, 19.0f magnetic material, connected by two blocks 20, 21, likewiseof magnetic material together constituting a permanent magnet in the form of a frame. This magnetic material of the two plates-1 8, 19 may for example be steel containing %40% of cobalt having a very great coercive force and strong residual magnet-ism. i

ne end of the winding of the coil 14 is connected through conductor 22 to the spindle 4 227,2 3, and in Switzerland- October 26, 1 926.

and to the mass of the-movement connected to a source of current not illustrated. The other end of the winding is connected through conductor 23 with a finger 24 (Fig. ;2 carried by the spindle 4 but insulated there rom and coming into contact in passing with two plates 25. rigidly secured .to an oscillating vertical spindle 26. These two plates 25 are connected by a conductor 27 to the second pole of the source; The arm 2 which carries the several parts is insulated from the spindle4by the jewel in which the spindle turns and from the plate 1. The spindle 26 which rotates between two portions of the arm 2 is cut away at 28 for a portion of its length so that it has a semi-circular section having a flat portion 28 upon which bears a plate spring 29 rigidly secured to a frame 30 oscillating about horizontal pivots 30 inthe arm 2, and provided with a projecting arm 31 to increase its weight. The weight of frame 30 and arm 31 compels spring 29 to bear against part 28 to return'spindle 26 to its normal position. v

The spindle 4 has at its lower end an eccentric 41 located within a fork 42 on an arm 43 integral with an oscillating spindle 44 providedwith a second arm 45 the latterhaving a spring pawl 46 for advancing by one tooth a ratchet wheel 47 at each oscillation of the balance wheel which is geared by gearwheels 48 to the'hand spindle such as 49.

A spiral hair spring 50 of conventional form is provided to maintain the balance wheel 5 in continuous isochronous oscillation.

The operation of this mode of construction is as follows:

In the course'of an oscillation in one direction the finger 24 comes into contact withthe plates 25 at a time a little before the moment when the coil14 enters the strong magnetic field between the two pole pieces. The contact is maintained until the coil 14 has nearly arrived at a position coaxial with the two pole pieces, at which time the coil 14 and the arm 13, to which it is attached, are at the center of their swing. The coil meanwhile is drawn into the magnetic field because of the current which passes during the interval of contact. At this point the finger 24 passes by the plates 25 which have been rotated by the pressure of the finger, and the plates are quickly returned to their original position because of the pres sure of the spring 29 on one edge of the plane portion 28 of the spindle 26. The magnetic impulse given in this operation is suflicient to maintain the spindle 4 and balance wheel 5 in continuous oscillations. On the return movement, the finger 24 displaces the plates 25 a small amount in the opposite sense, suificient to allow the finger to pass. The plates are once more returned to their initial position because of the pressure of the spring 29 on the other edge of the plane portion 28. is not necessary but the back of the finger 24 may be covered with an insulating material so that no electrical current is wasted during the return movement of the balance wheel.

The employment of cobalt steel enables a magnet of small volume affording an intense field, to be obtained. The fact that the spindle 26 is returned to its position of rest by gravity acting on frame 30 and arm 31 has this advantage that it aflords the possibility of exactly regulating the resistance opposed to its rotation by modification of its weight and of maintaining this resistance practically constant even in the course of a long operation of the movement.

What I claim as new and desire to secure by Letters Patent of the United States is 2- 1. In an electric clock having an oscillatin member carrying a coil, a magnetic fiel through which the coil passes, an electric circuit including said coil, in combination, a contact connected to said circuit carried by the oscillating member a second contact also connected to said circuit normallyseparated from the first contact and arranged to be engaged by the first contact to complete said circuit when the coil is in the magnetic field and gravity controlled means horizontally pivoted and connected to said second contact for returning said second contact to its normal position after displacement.

2. In an electric clock having on oscillating member carrying a coil, a magnetic field to this specification at t October, 1927.

plates intermediate the supports with an air gap between them through which the coil is adapted to oscillate.

4. In an electric clock having an oscillating member carrying a coil, a permanent magnet comprising a frame consisting of two parallel plates spaced apart in parallel relation, supports connecting the plates at opposite ends, and pole pieces secured to the center of the plates with an air gap between them through which the coil is adapted to oscillate.

In witness whereof I. have signed my name FRANK HOLDEN.

through which the c011 passes, an electric circuit including said coil, in combination, a contact connected to said circuit carried by the oscillating member a second vertically pivoted contact also connected to said circuit normally separated from the first contact and arranged to be engaged by the first contact to complete said circuit when the coil is in the magnetic field and a gravity controlled horizontally pivoted frame adapted to engage the second contact after displacement and to return it to its normal position.

3. In an electric clock having an oscillating member carrying a coil, a magnet comprising two plates of magnetic material spaced apart in parallel relation, supports of magnetic material connecting the opposite ends of the plates, and magnet pole pieces secured to Milan this 3rd day of 

